A diamond quantum sensor enables one current comparator to measure AC and DC ratios, simplifying calibration while reducing comparator size and mass for power systems.
The National Institute of Advanced Industrial Science and Technology (AIST), with the Institute of Science Tokyo and the National Institutes for Quantum Science and Technology, has developed a diamond-quantum-sensor-based current comparator that measures both AC and DC current ratios using one setup. The technology could simplify calibration equipment used for electrical power measurement.
Current comparators are used to evaluate and calibrate instruments that measure electrical current in power generation, transmission and distribution systems. Conventional approaches generally require different measurement principles and equipment for AC and DC currents, increasing the complexity of calibration systems.
The researchers demonstrated that a diamond quantum sensor can detect magnetic flux generated by electrical currents and use this information to evaluate current ratios for both AC and DC signals. The approach replaces the detection coil based on electromagnetic induction that is conventionally used for AC current-ratio measurements.
The quantum sensor operates by detecting magnetic fields associated with current flow. By using the same sensing principle for both current types, the developed comparator can perform AC and DC measurements without switching to separate comparator configurations. This could help streamline calibration procedures and reduce the equipment required for high-precision electrical measurements.
The new design also reduces the physical size of the comparator. According to AIST, eliminating the conventional detection coil reduced the central section to less than one-third of the size and less than one-tenth of the mass of conventional current comparators.
The researchers reported a 10⁻⁸-level type-A uncertainty for the current-ratio measurements, demonstrating the precision required for electrical metrology applications. The work was published in Scientific Reports under the title Current comparator for both AC and DC ratio measurements with 10⁻⁸-level type-A uncertainty.
The technology could support more compact and unified calibration systems for current-measurement instruments. AIST also expects the approach to contribute to measurement standardisation for future power networks where AC and DC systems increasingly operate alongside renewable-energy infrastructure.
